Welcome to the AC Tropical Fish aquarium forum. Our aquarium forum is the place to discuss any aquarium related issue in a friendly environment. Our aquarium forum welcomes aquarists of all levels from beginners to experts. Please ask a question in the how to section of our forum or read the FAQ section if you have any questions. register to and become a part of our friendly aquarium forum community today.

Mine is in my canister so the canister's flow handles/provides for that issue; they help with algae but will not pervent its growth if you do not maintain low nitrates; good water quality is the key reguardless of the UV. That said, can't hurt but don't get too high of a wattage - it just waste electricity and has more expensive bulbs; speaking of which, I keep one spare UV bulb (and, of course, and far more critically - a heater) on hand since ordering will take one week to ten days.

Knowledge is fun(damental)

A 75 gal with eight Discus, fake plants, and a lot of wood also with sand substrate. Clean up crew is down to just two Sterba's Corys. Filters: continuous new water flow; canister w/UV, in-tank algae scrubber!! Finally, junked the nitrate removal unit from hell.

I'm sorry, but the site listed has almost nothing accurate in the area discussing dwell time. A 9 watt UV unit at any water flow is good for green water up to about 30 gallons. It won't kill bacteria or viri on that tank, only green water. Will it kill enough of the algae in the water to eventually clear a 75g tank? Not if the algae is actively reproducing. A diatomaceous earth filter would probably work better and cost less. Dealing with the imbalance in nutrients would cost far less.

dbosman, I'm trying to deal with a fert/light imbalance at the moment. Right now, I'm in the process of cutting back dosing of liquid ferts, which I think is the biggest problem. I was dosing about 3x per week. I've now cut that down to once per week and also started dosing co2 within the last two weeks. I'm hoping that cuts down on algae growth.

I think the inherent problem is that I allowed algae to grow in the first place. Now it has a stranglehold on my tank and won't let go. I had an imbalance for several months which lead to algae growth... so I think balancing things out might take about a month to see some visual effects.

Since posting this and reading up on UV sterilizers, the only reason I'd actually buy one is to rid the tank of a percentage of disease causing bacteria/viruses, as I don't have any standing algae, which leads to green water.

That being said, other than some sicknesses here and there, I really don't have any water quality problems. On an average week, I have 0 amm, 0 trites, 0-.25 trates, 0 phos & 7ph (now 7.6ph). That's with a weekly 50% w/c.

I'm attributing my disease problem to bad stock and possible stress from a change in pH. I added rocks (the same rocks I started with) to the tank, which I believe raised the pH from 7.0 to 7.6. That may have caused stress and possible osmotic shock. Now that I'm aware of what occurs with these rocks, I'm going to be leaving them in the tank, so that I no longer have fluctuations.

I don't think a UVS will be necessary, but the previous comments were helpful, nonetheless. I've learned quite a bit today.

I've been looking it one as well and it seems that they are only effective at killing harmful pathogens when they appropriately matched to the tank size and flow rate. From my bit of research, theres no perfectly matched unit to the specs of your tank so you almost always need to go bigger, which becomes more expensive as Cermet pointed out.

I had looked into adding a UV for my my reef tanks. To me they seam like a control measure rather than a preventative measure. If the conditions are right for algae, you will get algae, just not as badly as you would have if you did not have a UV. If you get ick in your tank, there will be less free swimming parasites in the water, but you will still have ick in your tank.

I hope that helps

If you take your time to do the research FIRST, you can successfully set-up and keep ANY type of aquarium with ease."Not using a quarantine tank is like playing Russian roulette. Nobody wins the game, some people just get to play longer than others." - Anthony CalfoFishless CycleCycling with FishMarine Aquarium Info [URL="http://saltwater.aquaticcommunity.com/"]

Thanks Cliff. That does help. It solidifies my thinking/reasoning behind not getting one. Personally, I'd like to solve the problem at the source and figure out how to keep the algae/sickness from happening. Not just attempt a quick fix, which may or may not work.

Appreciate it!

HP - I think it would probably be much more cost-effective to find the source of the problem, rather than throw $100 at it to see if something might work. I was hoping it would be a preventative measure, but the more people chime in and the more I read, the more likely this preventative measure wouldn't really do me a whole lot of good.

l run a UV light 24/7. It is very important to match the flow of water with what you want it to do. A lower flow of water kills parasites and fish disease. You want a kill rate at 75,000 uw/cm -90,000 kill rate. With this high kill rate it will not be good for live rock or reef inverts. The lower kill rate is ideal for reef environment- 30,000 to 45,000. The higher kill rate will destroy planktonic food supply for the reef. It is important to have a quartz sleeve surrounding your light.